Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$182.55	7.664%	$196.5406	$196.54	$196.55	$196.50
Purchase #2	$221.69	4.848%	$232.4375	$232.44	$232.45	$232.40
Purchase #3	$59.97	10.854%	$66.4791	$66.48	$66.50	$66.50
Purchase #4	$220.55	6.302%	$234.4491	$234.45	$234.45	$234.40
Purchase #5	$92.46	10.402%	$102.0777	$102.08	$102.10	$102.10
Purchase #6	$220.26	10.278%	$242.8983	$242.90	$242.90	$242.90
Purchase #7	$73.45	6.759%	$78.4145	$78.41	$78.40	$78.40
7 purchase totals =	$1,070.93		$1,153.2968	$1,153.30	$1,153.35	$1,153.20